GB2283926A - Filter - Google Patents

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Publication number
GB2283926A
GB2283926A GB9420978A GB9420978A GB2283926A GB 2283926 A GB2283926 A GB 2283926A GB 9420978 A GB9420978 A GB 9420978A GB 9420978 A GB9420978 A GB 9420978A GB 2283926 A GB2283926 A GB 2283926A
Authority
GB
United Kingdom
Prior art keywords
filter
partially fused
particles
reinforcing structure
fused particles
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB9420978A
Other versions
GB2283926B (en
GB9420978D0 (en
Inventor
Ian Christison Sayers
Thomas Saunders
Andrew Allum
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Scapa Group Ltd
Original Assignee
Scapa Group Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB939323620A external-priority patent/GB9323620D0/en
Priority claimed from GB9414981A external-priority patent/GB9414981D0/en
Application filed by Scapa Group Ltd filed Critical Scapa Group Ltd
Priority to GB9420978A priority Critical patent/GB2283926B/en
Publication of GB9420978D0 publication Critical patent/GB9420978D0/en
Publication of GB2283926A publication Critical patent/GB2283926A/en
Application granted granted Critical
Publication of GB2283926B publication Critical patent/GB2283926B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/08—Filter cloth, i.e. woven, knitted or interlaced material
    • B01D39/083—Filter cloth, i.e. woven, knitted or interlaced material of organic material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/14—Other self-supporting filtering material ; Other filtering material
    • B01D39/16—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres
    • B01D39/1638—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being particulate
    • B01D39/1653—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being particulate of synthetic origin
    • B01D39/1661—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres the material being particulate of synthetic origin sintered or bonded
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/14—Other self-supporting filtering material ; Other filtering material
    • B01D39/20—Other self-supporting filtering material ; Other filtering material of inorganic material, e.g. asbestos paper, metallic filtering material of non-woven wires
    • B01D39/2027—Metallic material
    • B01D39/2031—Metallic material the material being particulate
    • B01D39/2034—Metallic material the material being particulate sintered or bonded by inorganic agents
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/24—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by surface fusion and bonding of particles to form voids, e.g. sintering
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F1/00—Wet end of machines for making continuous webs of paper
    • D21F1/0027—Screen-cloths
    • D21F1/0063—Perforated sheets
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F7/00—Other details of machines for making continuous webs of paper
    • D21F7/08—Felts
    • D21F7/083—Multi-layer felts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/02—Types of fibres, filaments or particles, self-supporting or supported materials
    • B01D2239/0216—Bicomponent or multicomponent fibres
    • B01D2239/0233—Island-in-sea
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/04—Additives and treatments of the filtering material
    • B01D2239/0471—Surface coating material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/06—Filter cloth, e.g. knitted, woven non-woven; self-supported material
    • B01D2239/065—More than one layer present in the filtering material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/06—Filter cloth, e.g. knitted, woven non-woven; self-supported material
    • B01D2239/065—More than one layer present in the filtering material
    • B01D2239/0654—Support layers

Abstract

A filter made from partially fused particles. The particles may be polymeric or may comprise a metal. The partially fused polymeric particles may be located on a base structure or a reinforcing structure may be embedded therein.

Description

FILTER The present invention relates to a filter and more particularly to a filter comprising partially fused particles.
A suitable particulate material can be partially fused by means of a high energy input to give a structure containing a multitude of interstices. When heated above their crystalline melting point, the particles do not fluidise, but adopt a viscoelastic form. The external shape of the individual particles is substantially retained so as to provide an array of contiguously dispersed neighbouring particles. Usually for the successful partial fusion of polymers ultra high molecular weight materials (UHMW) must be used, a typical molecular weight being 3 to 9 x 106 g/mol.
However, some materials such as polyurethane and thermoplastic polyurethane do not need to possess an ultra high molecular weight for successful particle fusion.
According to the present invention there is provided a filter comprising partially fused particles.
The particles are preferably polymeric, although other materials such as metals maybe used.
For example, the partially fused particles may be provided as a coating on a base material such as a fabric.
This coating may be partially fused in situ. Alternatively the partially fused particles are not provided as a coating, but in sheet form, optionally comprising a reinforcement structure embedded within the sheet.
The partially fused polymer exhibits toughness, abrasion resistance, chemical resistance, heat stability, low coefficient of friction, an easy-clean surface and hydrophobicity.
Preferred polymers for partial particle fusion include polyalkenes such as polyethylene and polypropylene, polyurethane, thermoplastic polyurethane or EPDM (ethylene propylene diene monomer). One example polymer is the Hostalon GUR (trade mark of Hoechst AG) range of UHMW polyethylene having a molecular weight of 3.2 to 8 x 106 g/mol. Another example is the Goodrich product 58810 (TM) which has a shore hardness of 90.
A sheet of partially fused polymer may be prepared by evenly spreading the polymer powder into a layer of uniform thickness of typically 3 to 4 mm and then heating the polymer.
The uniform polymer layer may be obtained by using a roller or blade. Alternatively the polymer powder may be moulded to the desired thickness. The layer of polymer is heated to say 2300C to 2400C for a time period in the order of 1.9 mins per mm of sheet thickness, allowing for shrinkage due to partial fusion forces. Continuous sheet production may involve distributing the powdered polymer onto a tensioned metal belt which passes through an oven where the belt is heated from above and underneath by IR heaters to facilitate partial fusion. The finished product may be mechanically treated, e.g. by grinding to give a smooth finish.
Some materials such as thermoplastic polyurethanes on being subjected to a high energy input partially fluidise and partially adopt a viscoelastic form as previously described so as to provide a partially fused product having superior toughness.
Other materials do not fluidise to a significant extent.
Such sheets of solely partially fused polymeric particles will have one drawback in that each polymer particle is only bonded at its tangent. The force required to break these bonds will not be particularly great and therefore a partially fused sheet will readily shed polymeric particles when subjected to frictional or impact forces. A reinforcement structure may be embedded wholly within such materials. This may comprise fibres extending through the partially fused product.
Alternatively the reinforcement may comprise a fabric such as a nonwoven fabric, a mesh fabric, a plain weave fabric or a random dispersion of chopped fibres.
Bonding or bicomponent fibres are preferred, the melting or softening point of which is greater than that of the polymeric particles. On a macro scale the fibres may be formed into yarns. The yarns may form a woven or nonwoven matrix.
An example bicomponent fibre is Danaklon ES-C (trade mark) which comprises a polyethylene core and a polypropylene sheath. The fibre has a high adhesion strength and a low bonding temperature-of 135 to 1450C. An example bonding fibre is Dacron 134 (trade mark of DuPont) which is a polyethylene terephthalate fibre with a melting/softening point of 2050C.
One particularly suitable fibre is polyamide 6, having a melting point of 2350C. A sheath core bicomponent fibre with a polyamide 6 sheath and polyamide 6:6 core may also be appropriate.
The permeability of the partially fused product may be improved by incorporating a blowing agent into the product during partial particle fusion or using a porous support medium (e.g. partially fused metal) to enable the partially fusible powder to be fluidised immediately prior to melt bonding.
The particles may be layered in different size fractions to produce a pyramidal porosity profile and, therefore, a permeability gradient. The partially fused sheet may be coated with fluoropolymers to give an improved wipe-clean, hydrophobic surface particularly advantageous for preventing re-wet of papermachine clothing and reducing fabric contamination. An ormocer (organically modified ceramic) coating would confer significant abrasion resistance, with back-flushing of air being employed at the point of lick-up during coating application to ensure the permeability of the structure is maintained.
A hybrid needled felt/partially fused particle surface may be formed by partially embedding polymer particles in the fibrous surface to act as a foundation for the final partially fused layer.
A further advantage of this method is the ease of addition of pigments, for example, a marking such as a bar may be incorporated to aid alignment of fabrics on machines and a logo can easily be incorporated.

Claims (16)

1. A filter comprising partially fused particles.
2. A filter as claimed in claim 1, wherein the said particles are polymeric.
3. A filter as claimed in claim 1 or claim 2, wherein the particles comprise a polyalkene, polyurethane or EPDM.
4. A filter as claimed in claim 1, wherein the said particles comprise a metal.
5. A filter as claimed in any preceding claim, wherein the partially fused particles are provided as a coating on a base material.
6. A filter as claimed in claim 5, wherein the base material comprises a fabric.
7. A filter as claimed in claim 1, wherein the partially fused particles are provided in sheet form.
8. A filter as claimed in claim 7, wherein a reinforcing structure is embedded within the sheet of partially fused particles.
9. A filter as claimed in claim 8, wherein the reinforcing structure comprises fibres extending through the mass of partially fused particles.
10. A filter as claimed in claim 8, wherein the reinforcing structure comprises a fabric.
11. A filter as claimed in claim 8, wherein the reinforcing structure comprises a random dispersion of chopped fibres.
12. A filter as claimed in any of claims 8 to 11, wherein the reinforcing structure comprises fibres having a melting or softening point which is greater than that of said partially fused particles.
13. A filter as claimed in any of claims 8 to 12, wherein the reinforcing structure comprises bonding or bicomponent fibres.
14. A filter as claimed in any preceding claim, wherein the partially fused particles are layered in different size fractions.
15. A filter as claimed in any preceding claim, having a fluoropolymer coating- thereon.
16. A filter as claimed in any preceding claim, having an ormocer coating thereon.
GB9420978A 1993-11-16 1994-10-18 Filter Expired - Fee Related GB2283926B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB9420978A GB2283926B (en) 1993-11-16 1994-10-18 Filter

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GB939323620A GB9323620D0 (en) 1993-11-16 1993-11-16 Partial particle fusion
GB9414981A GB9414981D0 (en) 1994-07-26 1994-07-26 Filter
GB9420978A GB2283926B (en) 1993-11-16 1994-10-18 Filter

Publications (3)

Publication Number Publication Date
GB9420978D0 GB9420978D0 (en) 1994-12-07
GB2283926A true GB2283926A (en) 1995-05-24
GB2283926B GB2283926B (en) 1998-01-14

Family

ID=27266936

Family Applications (1)

Application Number Title Priority Date Filing Date
GB9420978A Expired - Fee Related GB2283926B (en) 1993-11-16 1994-10-18 Filter

Country Status (1)

Country Link
GB (1) GB2283926B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20190336890A1 (en) * 2016-10-31 2019-11-07 Flsmidth A/S Snap-On Porous Filter Media For Filter Press Plates

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5481564A (en) * 1977-12-09 1979-06-29 Tamotsu Morimasa Filtration method
US5332426A (en) * 1992-07-29 1994-07-26 Minnesota Mining And Manufacturing Company Agglomerated activated carbon air filter

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE606897A (en) * 1960-08-18 1900-01-01
FR2462188A1 (en) * 1979-07-25 1981-02-13 Tissmetal Lionel Dupont Filter for gases or liq. - where substrate fabric or felt is covered by grains of thermoplastic polymer bonded to fabric by heating
US4690763A (en) * 1982-09-29 1987-09-01 Swiss Aluminium Ltd. Filter medium in the form of a stable porous body
GB9007304D0 (en) * 1990-03-31 1990-05-30 Gore W L & Ass Uk Filter element
DE4201559A1 (en) * 1992-01-22 1993-07-29 Schwaebische Huettenwerke Gmbh MATERIAL FOR FILTERS, IN PARTICULAR OIL, GASOLINE OR DIESEL FILTERS OF MOTOR VEHICLES
DE4211529A1 (en) * 1992-04-06 1993-10-07 Herding Entstaubung Filter element with a dimensionally stable, permeable-porous plastic molded body

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5481564A (en) * 1977-12-09 1979-06-29 Tamotsu Morimasa Filtration method
US5332426A (en) * 1992-07-29 1994-07-26 Minnesota Mining And Manufacturing Company Agglomerated activated carbon air filter

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
WPI Accession Number 79-59033B/32 & JP 54081564 A *
WPI Accession Number 90-193630/25 & ZA 8905040 A *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20190336890A1 (en) * 2016-10-31 2019-11-07 Flsmidth A/S Snap-On Porous Filter Media For Filter Press Plates

Also Published As

Publication number Publication date
GB2283926B (en) 1998-01-14
GB9420978D0 (en) 1994-12-07

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Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee

Effective date: 20001018